Isolating switches equipped with cartridge fuses



June 13, 1967 Filed Dec. 16, 1965 C. SCHNEIDER ETAL ISOLATING SWITCHES EQUIPPED WITH CARTRIDGE FUSES 5 Sheets-Sheet 1 June 13, 1967 c. SCHNEIDER ETAL 3,325,615

ISOLATING SWITCHES EQUIPPED WITH CARTRIDGE FUSES Filed D80. 16, 1965 5 Sheets-Sheet 2 June 13, 1967 SCHNEIDER ETAL 3,325,615

ISOLATING SWITCHES EQUIPPED WITH CARTRIDGE FUSES Filed Dec. 16, 1965 5 Sheets-Sheet 3 June 13, 1967 SCHNHDER Em 3,325,615

ISOLATING SWITCHES EQUIPPED WITH CARTRIDGE FUSES Filed Dec. 16,- 1965 5 Sheets-Sheet 4 27 3:? I j a -28 ISOLATING SWITCHES EQUIPPED WITH CARTRIDGE FUSES J 3, 1967 c. SCHNEIDER ET'AL 5 Sheets-Sheet 5 Filed Dec.

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Kim. pioous Patented June 13, 1967 3,325,615 ISGLATING SWITCHES EQUIPPED WITH CARTRIDGE FUSES Eharles Schneider, Asnieres, Seine, and Daniel Caporossi, Epinay, Seine, France, assignors to La Telemecanique Eiectrique, Nanterre, Seine, France, a French body corporate Filed Dec. 16, 1965, Ser. No. 514,330 Claims priority, application France, Dec. 28, 1964, 82 11 Claims. (Cl. 200-114) Various constructional forms of isolating switches which employ cartridge fuses whose conductive ends are formed into blades and co-operate with clamp or jaw contacts are already known. In those devices, a movable arrangement carrying a set of cartridge fuses and such that the conductive ends of the latter are free enables all the cartridge ends to be engaged in or disengaged from fixed co-operating contacts at one end and the same time, generally through the medium of an operating lever.

In particular, there is known from German Patent No. 1,076,775 dated April 24, 1956, a fuse-equipped isolating switch in which the moveable part of the switch is a cover carrying the bladed cartridges on its inner face, the cover being provided, at its ends, with two pinions fast with an operating handle and rotating on a common axis to mesh with fixed racks normal to the base of the isolating switch carrying the clamps co-operating with the blades. At the end of the withdrawing movement of the cover, the latter can tilt and this facilitates access to the cartridges for the purpose of replacing them.

In this known construction, the pinions ensure a constant reduction of the force required for manually withdrawing the blades from their respective clamps, and, moreover, this known isolating switch does not by itself permit the testing of auxiliary circuits when the switch is open.

The present invention relates to an isolating switch which does not exhibit those drawbacks.

The invention provides an isolating switch comprising a cover movable with respect to a fixed base carrying fuse contacts and bearing on its inner face, cartridge fuses cooperating with the said fuse contacts, the cover being adapted to be operated by two mechanisms located at its ends and being able to swing into a position perpendicular to its normal position at the end of the movement of withdrawal of the cartridges, wherein the cover is hingedly mounted between two slides movable at right angles to the base and each controlled through the medium of a cam by means of a shaft turning in bearings fixed to the base, the shaft moreover acting on movable contacts co-operating with further contacts fixed to the base, these further contacts being connectable into auxiliary circuits.

In such a construction, the cover being held in position perpendicular to the base, if the isolating switch is operated, only the auxiliary circuits are closed, the cartridge fuses being then in a position such that they cannot engage the fuse contacts. It is thus possible to check for satisfactory operation of the auxiliary circuits without putting the main circuits under voltage.

Preferably, the movable auxiliary contacts are carried by the control shaft through the medium of springs ensuring pressure of the contacts on the further fixed contacts, while in the closed position of the isolating switch the shaft is subjected to a resilient torque which keeps the contacts closed.

To this end, in an advantageous constructional form of the invention, each of the ends of the control shaft is associated with a crank connected to one end of a spring the other end of which is fixed, the position of alignment of the axis of the shaft, the crank and the outer fixed point of attachment of the spring corresponding to an intermediate position of the shaft in its movement of control of the slides. Thus, the same springs which keep the auxiliary contacts closed in the closed position of the isolating switch also act in the open position of the latter to keep the shaft in the corresponding position.

The cams acting on the slides are preferably slots cut in plates connected for rotation with the control shaft towards the ends of the latter, the slots engaging with studs projecting from the slides. The slots are preferably L-shaped and have an essentially radial long side or arm and a short side or arm disposed at that end of the long side which is further from the shaft and having the form of a portion of a circle having the shaft as its centre. The essentially radial part of these slots causes the displacement of the slides; owing to the orientation of this portion of the slot, the effort which must be produced at the operating handle connected to the control shaft and the diagram of the linear movements of advance of the slides are of tangential form and this simultaneously produces a reduction of the forces and an acceleration of the speed of opening. In the open position of the isolating switch, the two slides are locked irreversibly in a position remote from the base by the engagement of the studs carried by them in the short arms of the L-shaped slots.

According to another subsidiary feature of the invention, the control shaft of the isolating switch is connected to the slot-carrying plates with an idle rotary motion, while the movable contacts of the auxiliary circuits which are carried by the shaft are connected directly to the shaft. To this end, the control shaft is advantageously of square cross-section and the plates carrying the slots forming cams have an opening of diamond shape for their rotation by the shaft.

In this way, due to the play of the shaft in the diamondshaped openings, when the rotation of the shaft in the direction of opening is initiated, the commencement of the rotation results in the opening of the movable auxiliary contacts before the horizontal translation of the slides which ensures the opening of the main contacts begins. The interruption of the auxiliary circuits obtained in this way consequently ensures the cutting off of any apparatus which might have remained under voltage, through the medium of main contactors or cut-outs associated with these circuits, and this permits with certainty the opening of the main circuits by the isolating fuses in the absence of voltage.

The description which follows with reference to the accompanying drawings, which is given by way of nonlimitative example, will make it clearly understood how the invention can be carried into effect.

In the accompanying drawings:

FIGURE 1 is a view in elevation of an isolating switch embodying the invention with fuses in position,

FIGURES 2a, 2b, 2c are sections on the line II-II of FIGURE 1 in the closed position of the isolating switch, in an intermediate position, and, in the open position of the switch respectively,

FIGURES 3a, 3b, 3c, and 4a, 4b, 4c are, respectively, sections on the lines IIIIII and IVIV of FIGURE 1 in the same positions as the FIGURES 2 with the same alphabetical index,

FIGURE 5 is a section of the isolating switch on the line VV in the open position of the switch,

FIGURE 6 is a section similar to FIGURE 5 showing the isolating switch in the test position, and,

FIGURE 7 is a view on the line VIIVII of FIG- URE 5.

The isolating switch shown in FIGURE 1 is a fourpole device. Seen in elevation in this figure, it is mounted between two end casings 1 which can be fixed by means of the holes 1a to a support panel, The casings each contain one of the operating mechanisms of the isolating switch, which mechanisms can be seen in FIGURES 2. The two casings 1 are connected by a pair of square cross-section bars 2 to which the fixed elements of the isolating switch are secured by means of screws 3 and plates 4 forming braces or clamps (see FIGURES 3c and 5 For each of the poles, the fixed elements comprise a base 5 (FIGURE 5) at each end of which there are fixed clamps 6 associated with flat terminals 7 for connection to main external conductors. U-shaped supports 8 carrying bearing pins 9 for springs ltl are fixed between the casings 1 by the screws 3 and plates 4.

The isolating switch is controlled by a square crosssection shaft 11 on the two ends of which there are placed and fixed bushings 12 having square cross-section bores, cylindrical peripheries and stop collars 12a, thereby enabling the shaft 11 to turn in bores formed in the casings 1. The shaft 11 is operated by a handle 13 which, when the isolating switch is closed, occupies the position shown in FIGURE 1 in full lines and, when the switch is open, the position 13 shown in FIGURE 1 in chain-dotted lines.

A flat plate 14 slides in each casing. The edges of the plate 14 slide in the slideways 1a of thecasing, the sliding action being facilitated by a lining 15 of a suitable plastics material, for example superpolyamide. The plate 14, which is suitably cut away at 14a to clear the shaft 11 and the square bars 2, carries a driving stud 16 screwed into a tapped hole in the plate, In order to permit removal, the outer face of the casing has a hole (not shown) giving access to the stud.

The stud 16 is engaged in a slot 18 of a plate 17 movable between the plate 14 and the outer wall of the casing. The slot 18 is L-shaped and it comprises a substantially radial, long portion 18a and a portion 18b which is in the form of a very short are of a circle whose centre lies on the axis of the shaft 11. The plate 17 is rotatively connected to the shaft through the medium of a hole 19 through which the shaft extends and which is shaped like a diamond whose points are cut away. Thus, as can be seen by comparing FIGURES 2a and 2b, the shaft 11 can turn freely through a certain angle before driving the plates 17 Fixed on the shaft 11 between the two arms of each U'shaped support 8 is a pair of discs 20 which are cut out at their peripheries in such manner as to form a crank, there being a pin 21 which connects the two discs. An elongated plate 22, extending through a coil spring 10, has at one end, a long fork 22a engaged over the fixed pin 9 and, at the other end, a short fork 22b in engagement with the movable pin 21. The short fork 22b is kept in position by the thrust of the spring 10 which, as has already been indicated, bears on the pin 9 and, at its other end, on a shoulder 22c of the elongated plate 22.

As can be seen by comparing FIGURES 3a and 3c during the operation of the isolating switch, the crankpin 21 passes from one side to the other of the line joining the geometrical axis of the shaft 11 and of the fixed pin 9, moving across an intermediate position in which the three axes are aligned and the spring 10 is subjected to maximum compression.

Also keyed on the shaft 11 is an insulating crank 23 which carries, in at least one place at right angles to the shaft 11, a contact bridge 24 subjected to the action of a spring 25. This contact bridge can co-operate with fixed contacts 26 provided with terminals 27 for connection to auxiliary circuits, the fixed contacts being supported by a base 28 likewise fixed to the square bars 2, either 4 directly by means of a screw 3 and a plate 4, or through the medium of the nearest base 5, to which the contacts 26 may be connected. The crank 23 can carry a plurality of bridges 24; in practice, it is advantageous to provide two bridges inserted in the two conductors supplying the auxiliary circuits.

Towards the rear of the device as seen in FIGURE 1, each plate 14 carries two plain fingers 29 and 30 designed to support the cover A of the isolating switch. This cover comprises two end elements 31 in which there are fixed the ends of two square cross-section bars" 32 having an insulated periphery and which are parallel to the bars 2.

For connection to the fingers 29 and 30, each end element 31 has adjacent its bottom an oval hole 31a and towards its top, a notch 31b in the form of a hook, the length of which corresponds to that of the oval hole 31a. Thus, as will be seen from FIGURE 30, the cover of the isolating switch can pivot about the pair of opposite fingers 29 when, after it has been lifted, its hook-shaped notches 31b are disengaged from the opposite fingers 30. The cover can thus adopt the position A shown in chaindotted lines.

To correspond with the bases 5 fixed to the square bars 2, the cover A has an equal number of fuse holders 33 which are mounted by being slipped on to the insulated bars 32 and are kept in position by means of spacers 34 which, as shown, may be simple flat plates seated in grooves in the end elements 31 and in the fuse holders 33.

Each fuse holder has, in its portion facing the corresponding base 5, two cavities 35 and 36, respectively, which are closed by the plates 37 each provided with a T-shaped opening 37a. Inside the cavity 36 there is a hairpin spring 38, one end of which is imprisoned at the back of the cavity 36 and the other end of which extends facing the opening 37a, the tip being directed towards the wide part of the T-shaped opening.

It is known that large-diameter fuses comprise at their ends (FIGURE 5) flat blades 39 disposed as extensions of one another, and a body 40. They are, moreover, equipped with T-shaped lugs 41 for fixing them to the movable parts of isolating switches. In the present case, these lugs 41 are introduced into the wide portions of the openings 37a against the action of the spring 38 (FIGURE 7) and the narrow portions of the T-shaped lugs 41 are then moved down into the narrow portions of the openings 37a. The springs 38 then keep the fuses in this position. The fuses are thus suspended from the fuse holders 33 and retain sufiicient freedom with respect to the cover A to be engaged with certainty and without forcing in the clamps 6 designed to receive their blades 39.

The fuse holders 33 also have openings 42 closed by transparent plates 43 for permitting inspection of the fuse body 40, which frequently comprises means indicating the state of the fuse. Finally, the series of fuse holders 33 is arranged to receive a strip 45 (FIGURE 1) on which an inscription relating to the isolating switch can be carried. The strip, which extends below all the lugs 46 of the fuse holders, is placed in position over the entire length of the cover A before the end elements 31 are fixed.

In the closed position of the isolating switch, the latter is in the state shown in FIGURES 2a, 3a and 4a, that is to say, the fuses 39, 40 are engaged in the clamps 6, the shaft 11, urged in a clockwise direction by the springs 10 (arrow F pressing the movable contact bridges 24, thus compressing the springs 25, against the fixed contacts 26 (FIGURE 4a). In this position, the square sides of the shaft 11 touch the edges of the opening 19 on those sides of these edges which correspond to the direction of rotation imposed by the spring 10. The main circuits and the auxiliary circuits are therefore in service.

To open the isolating switch, the handle 13 is operated in the direction of the arrow F in FIGURES 1, 3b, 4b. The rotation of the shaft 11 is effected at first in opposition to the spring 10 without driving the plates 17 during that angle of rotation in which the sides of the shaft pass from one of the edges of the angles of the opening 19 to the other. During this movement, the insulating crank 23 carrying the contact bridges 24 is carried along, the springs 25 relax and the bridges are separated from the fixed contacts, thereby opening the auxiliary circuits.

The plates 17, which have not yet been rotated (FIG- URES 2a and 2b), are still in a position such that the stud 16 of each of the plates 14 is in that end of the slot 18 which is closest to the shaft 11 and level with the shaft 11, the long arm of the slot 18 being directed towards the support panel of the isolating switch.

As the movement of rotation of the shaft 11 is continued, the plates 17 are rotated and the bottom of the slot 18 and then that edge of the latter which is on the right in FIGURE 2b begin to act on the corresponding stud 61 to carry the plates 14 and, consequently, the cover A in the direction in which the cover is moved away from the bases 5.

At the beginning of the movement, the stud 16 is very close to the shaft 11, so that the force exerted on the handle 13 is transmitted to the stud 16 with a large lever arm ratio, as the long arm of the slot 18 is not exactly radial with respect to the shaft 11, but is offset forwardly in the direction of rotation which corresponds to opening, this position is prolonged during a rather large angle of rotation of the handle, so that a relatively small force or eifort is sufiicient at the beginning to carry the movable assembly along and disengage the blades 39 from the clamps 6. Then, as the rotation of the handle 13 progresses the distance of the stud 16 from the shaft 11 becomes larger and larger and, consequently, the movement of the cover A is more and more rapid for the same speed of the handle. This final movement is assisted by the fact that, substantially at that instant when the blades 39 are released from the clamps 6, the springs pass over centre and can expand to contribute towards the driving of the shaft 11 towards the open position of the isolating switch. In this way, the position shown in FIGURES 3c and 4c is finally reached, in which the plates 14 are locked by the engagement of the studs 16 in the portions 18b of the slots to prevent operation of the isolating switch without acting on the handle 13.

It has been seen that it is possible to cause the cover A to tilt about the pair of fingers 29. In this position, the fuses are accessible and can easily be disengaged.

Moreover, as shown in FIGURE 6, in the tilted position of the cover A, it is possible, by operating the handle 13 in the direction in which the isolating switch is reclosed (arrow F to bring the plates 14 back into the position corresponding to such closing, the fuses 39, 40, however, not coming into engagement with the clamps 6. However, as the crank 23 has caused the bridges 24- to touch the fixed contacts and the springs 10 have relaxed to press these contact bridges, the device is in the test position, since its auxiliary circuits are supplied without the main circuits being supplied.

It is obvious that modifications may be made in the form of embodiment which has just been described, in particular by substituting equivalent technical means, without thereby departing from the scope of the present invention.

We claim:

1. An isolating switch comprising in combination a base member, a cartridge fuse carrying member, fuse engaging contacts mounted upon said base member, mounting members slidably mounted upon said base member, pivotal mountings upon said mounting members for securing said fuse carrying member to said mounting members for movement to and from a position in which removal and insertion of cartridge fuses can be effected, a shaft rotatably mounted upon said base member, cams on said shaft and connected to said mounting members for sliding the latter with respect to said base member upon rotation of said shaft to engage and disengage each cartridge fuse and its fuse engaging contacts, fixed auxiliary electrical contacts mounted upon said base member and movable auxiliary electrical contacts for co-operation with said fixed auxiliary electrical contacts carried by said shaft.

2. An isolating switch as claimed in claim 1 and further comprising, in the mounting of said movable auxiliary electrical contacts, resilient means for exerting contact pressure between said fixed and movable auxiliary electrical contacts, and further resilient means for resiliently biasing said shaft to an isolating switch closed position.

3. An isolating switch as claimed in claim 1 and further comprising as each of said cams, a plate rotatively mounted upon said shaft at right angles to the longitudinal axis of the latter, a slot in said plate, said slot being substantially radial to said shaft, and projections on said mounting means, each said projection being engaged in one of said slots.

4. An isolating switch as claimed in claim 3 in which said slot is of L-shape having a long limb off-set forwardly with respect to the radial direction in the sense of rotation of said shaft corresponding to the opening of the isolating switch, said slot also having a short limb located at that end of said long limb remote from said shaft, said short limb being in the form of the arc of a circle centred on the axis of rotation of said shaft.

5. An isolating switch as claimed in claim 2 wherein said resilient biasing means comprises in combination, a coil spring mounted between a fixed point and a crankpin carried by said shaft disposed in such manner that the position of alignment of the shaft, the crankpin and the fixed point corresponds to a position of said shaft intermediate an isolating switch open position and an isolating switch closed position.

6. An isolating switch as claimed in claim 5 and further comprising a flat elongated member on which said coil spring is mounted, said flat elongated member lying in a plane at right angles to the longitudinal axis of said shaft and having a first fork part, a fixed pin embraced by said first fork part and supporting one end of said coil spring, a shoulder on said flat elongated member forming a support for the other end of said coil spring, and a second fork part on said flat elongated member remote from said first fork part in contact with said crankpin, said coil spring pressing said second fork part against said crankpin.

7. An isolating switch as claimed in claim 1 and further comprising, on said mounting members, facing fingers forming said pivotal mountings, and, spaced from said facing fingers, locking members for locking said fuse carrying member to said mounting members.

8. An isolating switch as claimed in claim 1 wherein said fuse carrying member comprises in combination, end pieces, bearings in said end pieces for permitting pivotal movement of said fuse carrying member, a plurality of juxtaposed cartridge fuse holders, spacers between adjacent cartridge fuse holders, and locking bars extending through said cartridge fuse holders and secured between said end pieces.

9. An isolating switch as claimed in claim 3 and further comprising a lost motion connector between said plates and said shaft.

10. An isolating switch as claimed in claim 9 wherein said shaft is of square transverse cross-section and is engaged in openings in said plates of substantially diamond shape.

11. An isolating switch as claimed in claim 2 and further comprising a crank of electrically insulating material secured on said shaft and a contact bridge mounted on said crank by means of said resilient means, said contact bridge being located in a plane at right angles to the longitudinal axis of said shaft.

(References on following page) References Cited UNITED STATES PATENTS West 200-50 Cuorato et a1. 20050 Baird et a1. 200114 Clark et a1 20050 Kurt 200-50 OTHER REFERENCES German printed application, 1,076,775, March 1960, Voss et a1., Isolating Switch.

German printed application, 1,157,287, November 5 1963, Zech at 211., Fused Isolator.

BERNARD A. GILHEANY, Primary Examiner.

H. E. SPRINGBORN, Assistant Examiner. 

1. AN ISOLATING SWITCH COMPRISING IN COMBINATION A BASE MEMBER, A CARTRIDGE FUSE CARRYING MEMBER, FUSE ENGAGING CONTACTS MOUNTED UPON SAID BASE MEMBER, MOUNTING MEMBERS SLIDABLY MOUNTED UPON SAID BASE MEMBER, PIVOTAL MOUNTINGS UPON SAID MOUNTING MEMBERS FOR SECURING SAID FUSE CARRYING MEMBER TO SAID MOUNTING MEMBERS FOR MOVEMENT TO AND FROM A POSITION IN WHICH REMOVAL AND INSERTION OF CARTRIDGE FUSES CAN BE EFFECTED, A SHAFT ROTATABLY MOUNTED UPON SAID BASE MEMBER, CAMS ON SAID SHAFT AND CONNECTED TO SAID MOUNTING MEMBERS 